1 /*
2 * Copyright (C) 2007 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 #include <objmng/drm_decoder.h>
18
19 /* global variables */
20 static const uint8_t * base64_alphabet = (const uint8_t *)"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
21
22 #define SKIP_CRLF(p) while('\r' == *(p) || '\n' == *(p)) \
23 p++
24
get_alphabet_index(int8_t ch)25 static int8_t get_alphabet_index(int8_t ch)
26 {
27 uint8_t * tmp;
28
29 if ('=' == ch)
30 return 64;
31
32 tmp = (uint8_t *)strchr((const char *)base64_alphabet, ch);
33 if (NULL == tmp)
34 return -1;
35
36 return (int8_t)(tmp - base64_alphabet);
37 }
38
39 /* See drm_decoder.h */
drm_decodeBase64(uint8_t * dest,int32_t destLen,uint8_t * src,int32_t * srcLen)40 int32_t drm_decodeBase64(uint8_t * dest, int32_t destLen, uint8_t * src, int32_t * srcLen)
41 {
42 int32_t maxDestSize, i, maxGroup;
43 uint8_t *pDest, *pSrc;
44 int8_t tpChar;
45
46 if (NULL == src || NULL == srcLen || *srcLen <= 0 || destLen < 0)
47 return -1;
48
49 maxDestSize = (*srcLen) * 3/4;
50 if (NULL == dest || 0 == destLen)
51 return maxDestSize;
52
53 if (destLen < maxDestSize)
54 maxDestSize = destLen;
55 maxGroup = maxDestSize/3;
56
57 pDest = dest; /* start to decode src to dest */
58 pSrc = src;
59 for (i = 0; i < maxGroup && *srcLen - (pSrc - src) >= 4; i++) {
60 SKIP_CRLF(pSrc);
61 if (pSrc - src >= *srcLen)
62 break;
63 tpChar = get_alphabet_index(*pSrc); /* to first byte */
64 if (-1 == tpChar || 64 == tpChar)
65 return -1;
66 pDest[0] = tpChar << 2;
67 pSrc++;
68 SKIP_CRLF(pSrc);
69 tpChar = get_alphabet_index(*pSrc);
70 if (-1 == tpChar || 64 == tpChar)
71 return -1;
72 pDest[0] |= (tpChar >> 4);
73 pDest[1] = tpChar << 4; /* to second byte */
74 pSrc++;
75 SKIP_CRLF(pSrc);
76 tpChar = get_alphabet_index(*pSrc);
77 if (-1 == tpChar)
78 return -1;
79 if (64 == tpChar) /* end */
80 return pDest - dest + 1;
81 pDest[1] |= (tpChar >> 2);
82 pDest[2] = tpChar << 6; /* to third byte */
83 pSrc++;
84 SKIP_CRLF(pSrc);
85 tpChar = get_alphabet_index(*pSrc);
86 if (-1 == tpChar)
87 return -1;
88 if (64 == tpChar) /* end */
89 return pDest - dest + 2;
90 pDest[2] |= tpChar;
91 pDest += 3;
92 pSrc++;
93 }
94 *srcLen = pSrc - src;
95 return pDest - dest;
96 }
97